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Cover of Elexacaftor-Tezacaftor-Ivacaftor and Ivacaftor (Trikafta)

Elexacaftor-Tezacaftor-Ivacaftor and Ivacaftor (Trikafta)

CADTH Reimbursement Recommendation

Indication: For the treatment of cystic fibrosis in patients aged 2 and older who have at least one F508del mutation in the cystic fibrosis transmembrane conductance regulator gene

Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; .
Report No.: SR0776

Summary

What Is the CADTH Reimbursement Recommendation for Trikafta?:

CADTH recommends that Trikafta be reimbursed by public drug plans for the treatment of cystic fibrosis (CF) in patients aged 2 to 5 years and older who have at least one F508del mutation in the CFTR gene, if certain conditions are met. The previous recommendation for Trikafta, for patients who initiate treatment at age 6 years or older, continues to apply to those patients.

What Are the Conditions for Reimbursement?:

Patients who start treatment with Trikafta should be evaluated for response after 1 year, and the treating physician must provide evidence after that the patient is benefiting from the treatment. The cost of Trikafta must also be reduced.

Why Did CADTH Make This Recommendation?:

For patients aged 2 to 5 years with CF, Trikafta was well tolerated and shown to improve lung function and reduce sweat chloride in an uncontrolled clinical trial. When used in patients aged 6 years and older, Trikafta was associated with meaningful improvements in lung function, nutritional status, and quality of life, and a reduced rate of pulmonary exacerbations. The committee acknowledged that conducting a comparative clinical study for Trikafta in patients aged 2 to 5 years may be ethically challenging, given the expected balance of risks and benefits of Trikafta in CF based on evidence in patients aged 6 years and older. Given the mechanism of action and efficacy data in patients with CF aged 6 years and older, Trikafta would be expected to benefit patients aged 2 to 5 years who have at least one F508del mutation in the CFTR gene.

Based on CADTH’s assessment of the health economic evidence, Trikafta does not represent good value to the health care system at the public list price. A price reduction is therefore required.

Based on public list prices, Trikafta is estimated to cost the public drug plans approximately $136 million over the next 3 years.

Additional Information

What Is CF?:

CF is a progressive, fatal, genetic disease that primarily affects the lungs and digestive system. Those living with CF lose the ability to breathe due to accumulated lung damage caused by chronic lung infections and inflammation. F508del is the most common mutation in the CFTR gene that results in CF.

Unmet Needs in CF:

There are significant unmet therapeutic needs for those living with CF. There are no treatments currently available that effectively meet the most important goals of CF therapy: to prolong survival, prevent the need for lung transplant, slow the decline in lung function over time, or reverse the course of the disease.

How Much Does Trikafta Cost?:

Treatment with Trikafta is expected to cost $306,810 per patient per year.

Recommendation

The CADTH Canadian Drug Expert Committee (CDEC) recommends that elexacaftor-tezacaftor-ivacaftor and ivacaftor (ELX-TEZ-IVA) be reimbursed for the treatment of cystic fibrosis (CF) in patients aged 2 to 5 years who have at least one F508del mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, only if the conditions listed in Table 1 are met.

The CDEC recommendation dated July 2022, for ELX-TEZ-IVA for the treatment of CF in patients who initiate treatment at age 6 years or older who have at least one F508del mutation in the CFTR gene, continues to apply to patients who are not included in the population of this recommendation.

Rationale for the Recommendation

CF is the most common fatal genetic disease affecting children and young adults in Canada. It is caused by mutations in the CFTR gene. Clinical expert input emphasized the importance of initiating treatment early in the disease course and that there is a significant unmet need for a treatment that would prevent disease progression and irreversible CF-related structural lung damage.

For patients aged 2 to 5 years with CF, a 24-week, open-label, uncontrolled trial (Study 111 part B; N = 75) suggested that treatment with ELX-TEZ-IVA resulted in improvements from baseline in lung function (decrease in lung clearance index 2.5% [LCI2.5] from baseline) and CF biomarkers (reduction in sweat chloride) and that the treatment was well tolerated. Study 111 was primarily designed to evaluate safety, tolerability, and pharmacokinetics of ELX-TEZ-IVA, as the regulatory submission was based on the extrapolation of efficacy data from the studies conducted in older patients with CF (i.e., those showing measurable levels of disease manifestations at baseline). Specifically, ELX-TEZ-IVA has demonstrated clinically meaningful improvements in lung function (increase in percent predicted forced expiratory volume in 1 second [ppFEV1]), nutritional status (increase in body mass index [BMI] z score), and health-related quality of life (increase in Cystic Fibrosis Questionnaire – Revised [CFQ-R] respiratory domain scores), and a reduced rate of pulmonary exacerbations, including events that required IV antibiotics and/or hospitalization in clinical trials conducted in patients aged 6 to 11 years (Study 116 [N = 121] and Study 106B [N = 66]) and in patients aged 12 years and older (Study 102 [N = 405], Study 103 [N = 107], Study 109 [N = 107], and Study 104 [N = 259]). CDEC has previously acknowledged that ELX-TEZ-IVA meets some of the important needs identified by patients with CF and their caregivers, such as reducing CF exacerbations, improving health-related quality of life, improving lung function, and improving digestive health allowing people to maintain a healthy body weight; the committee acknowledged that, given the mechanism of action and efficacy data in patients with CF aged 6 years and older, ELX-TEZ-IVA would be expected to benefit patients aged 2 to 5 years who have at least one F508del mutation in the CFTR gene.

Using the sponsor-submitted price for ELX-TEZ-IVA and publicly listed prices for all other drug costs, the incremental cost-effectiveness ratio (ICER) for ELX-TEZ-IVA was $1,284,953 per quality-adjusted life-year (QALY) gained in the F/F genotype, $1,451,526 per QALY gained in the F/MF genotype, $1,284,853 per QALY gained in the F/Gating genotype, and $1,644,869 per QALY gained in the F/RF genotype, compared to best supportive care. Additionally, ELX-TEZ-IVA was associated with an ICER of $838,687 per QALY gained when compared to LUM-IVA in the F/F genotype population. At these ICERs, ELX-TEZ-IVA is not cost-effective at a $50,000 per QALY gained willingness-to-pay threshold for the treatment of CF in patients aged 2 to 5 years who have at least one F508del mutation in the CFTR gene. A price reduction is required for ELX-TEZ-IVA to be considered cost-effective at a $50,000 per QALY gained threshold.

Table 1. Reimbursement Conditions and Reasons.

Table 1

Reimbursement Conditions and Reasons.

Discussion Points

  • There was uncertainty in the clinical evidence; therefore, the committee deliberated on ELX-TEZ-IVA considering the criteria for significant unmet need that are described in section 9.3.1 of Procedures for CADTH Reimbursement Reviews. Considering the rarity and severity of the condition, and the absence of clinically effective alternatives, the committee concluded that the available evidence reasonably suggests that ELX-TEZ-IVA could substantially reduce morbidity and/or mortality associated with CF.
  • The committee noted that nearly all patients in Canada aged 12 years and older who are eligible for treatment have initiated therapy with ELX-TEZ-IVA and that it is anticipated that nearly all patients aged 6 to 11 years will have initiated treatment with ELX-TEZ-IVA by the end of 2023. For those who have initiated treatment with ELX-TEZ-IVA, the clinical experts consulted by CADTH and the sponsor have indicated that initial renewal criteria were met for all patients in Canada who started the therapy and wanted to continue (i.e., 100% of patients met the renewal criteria recommended by CADTH and/or applied by the public drug programs).
  • The committee noted that input from patient groups, clinician groups, and the clinical experts consulted by CADTH emphasized the importance of initiating treatment with ELX-TEZ-IVA early in the disease course to try to prevent disease progression and irreversible damage. The clinical experts consulted by CADTH noted that many parents and caregivers would seek to initiate treatment for their child as early as possible (i.e., beginning at 2 years of age) and are anxiously awaiting access to ELX-TEZ-IVA for those who are currently younger than 6 years.
  • The committee discussed the applicability of the existing reimbursement conditions for those aged 6 years and older to those aged 2 to 5 years. The clinical experts noted that the following baseline measurements that are currently recommended by CADTH would be challenging to implement, uninformative, and/or not relevant for patients aged 2 to 5 years: baseline FEV1 (spirometry is not performed in patients younger than 6 years); baseline frequency of pulmonary exacerbations (exacerbations can be infrequent and it would be challenging establish a reliable baseline); and CFQ-R respiratory domain score (this is not routinely obtained in pediatric clinics and the instrument has not been validated for the age group of interest). The clinical experts noted that those aged 2 to 5 years would have growth parameters monitored in routine clinical practice. However, it was noted that a majority of patients with CF aged 2 to 5 years do not show reductions in age-standardized BMI and that BMI percentile can fluctuate in younger patients, especially following periods of acute illness.
  • The regulatory submission for ELX-TEZ-IVA for patients aged 2 to 5 years is based on the extrapolation of efficacy data from older age groups to a younger population based on comparable pharmacokinetic exposures and safety. The committee agreed with the clinical experts consulted by CADTH that, given the mechanism of action and efficacy data in patients with CF aged 6 years and older, ELX-TEZ-IVA would be expected to benefit patients aged 2 to 5 years who have at least one F508del mutation in the CFTR gene.
  • CDEC discussed ethical and equity considerations related to ELX-TEZ-IVA, including those related to the significant burden of living with CF. The committee also discussed how patients aged 2 to 5 years may be considered particularly vulnerable given that they are dependent on their parents to provide the necessities of life, and in the context of CF, to advocate and facilitate access to their diagnosis and support for their condition. CDEC discussed how the extrapolation of efficacy of ELX-TEZ-IVA in patients aged 2 to 5 years may be ethically justified in pediatric populations where it can avoid exposing vulnerable patients to unnecessary research, and discussed extending access to therapy in these patient populations. The clinical experts consulted by CADTH noted that when considering possible benefits and harms, they would prescribe ELX-TEZ-IVA for children aged 2 to 5 years, given the expected benefits of treatment to prevent the onset of CF-related structural lung damage. The committee also noted the potential advantages of using ELX-TEZ-IVA as an orally administered medication, including potential benefits for patients impacted by low socioeconomic status. The committee discussed potential disparities in access related to inconsistencies in insurance coverage or reimbursement of ELX-TEZ-IVA within Canada, and the significant costs associated with the use and implementation of ELX-TEZ-IVA.
  • CDEC discussed the absence of direct or indirect comparisons for ELX-TEZ-IVA versus other CFTR modulators approved for use in patients aged 2 to 5 years. The committee discussed the ethical challenges of conducting a comparative clinical study in this age group and potential concerns regarding the absence of clinical equipoise, given the evidence from patients aged 6 years and older where ELX-TEZ-IVA was shown to be superior to all other CFTR modulators currently marketed in Canada.
  • The sponsor’s submitted pharmacoeconomic evaluation assessed the cost-effectiveness of ELX-TEZ-IVA to best supportive care (BSC) or lumacaftor-ivacaftor (LUM-IVA) (for the F/F genotype only) over a 2- to 5-year-old patient’s entire lifetime. CDEC discussed how this decision problem does not accurately reflect the current landscape of CF treatment, as the majority of patients aged 6 years and older are currently being treated with ELX-TEZ-IVA, and thus a more appropriate decision problem would be to assess the cost-effectiveness of starting ELX-TEZ-IVA in patients aged 2 to 5 years versus waiting to initiate treatment at age 6 years or older. The cost-effectiveness of ELX-TEZ-IVA in the latter scenario is unknown.

Background

Trikafta is a fixed-dose combination product containing elexacaftor, tezacaftor, and ivacaftor co-packaged with ivacaftor (ELX-TEZ-IVA). ELX-TEZ-IVA is available as both oral tablets and oral granules in the following dosage strengths.

Tablets for patients aged 6 years and older:

  • elexacaftor 50 mg, tezacaftor 25 mg, and ivacaftor 37.5 mg, co-packaged with a tablet containing ivacaftor 75 mg
  • elexacaftor 100 mg, tezacaftor 50 mg, and ivacaftor 75 mg, co-packaged with a tablet containing ivacaftor 150 mg.

Granules for patients aged 2 years to younger than 6 years:

  • elexacaftor 100 mg, tezacaftor 50 mg, and ivacaftor 75 mg (granules), with ivacaftor 75 mg (granules)
  • elexacaftor 80 mg, tezacaftor 40 mg, and ivacaftor 60 mg (granules), with ivacaftor 59.5 mg (granules) (oral).

ELX-TEZ-IVA is indicated for the treatment of CF in patients aged 2 years and older who have at least one F508del mutation in the CFTR gene. F508del is the most common mutation in the CFTR gene that results in CF. The Canadian Cystic Fibrosis Registry reported that there were 4,344 people in Canada living with CF in 2019. Of these, 87.8% carried at least one F508del mutation (47.1% were homozygous and 40.7% were heterozygous).

This is the third submission to CADTH for ELX-TEZ-IVA. CADTH has previously reviewed ELX-TEZ-IVA for the treatment of CF in patients who have at least one F508del mutation in the CFTR gene for those aged 12 years and older (final recommendation issued in August 2021) and those aged 6 years and older (final recommendation issued in June 2022). For both of the previous reviews, CDEC recommended that ELX-TEZ-IVA be reimbursed with conditions. All of the indications for ELX-TEZ-IVA were accepted as priority reviews by Health Canada.

Sources of Information Used by the Committee

To make its recommendation, the committee considered the following information:

  • a review of a 24-week, open-label, phase III, nonrandomized, single-arm, open-label study in patients aged 2 to 5 years with at least an F/F or F/MF CFTR genotype
  • patient perspectives gathered by a patient group, Cystic Fibrosis Canada (CF Canada)
  • input from public drug plans and cancer agencies that participate in the CADTH review process
  • 4 clinical specialists with expertise diagnosing and treating pediatric patients with CF
  • input from 2 clinician groups, including CF Canada’s Accelerating Clinical Trials Network (CF CanACT) and the CF Canada Health Care Advisory Council
  • a review of the pharmacoeconomic model and report submitted by the sponsor
  • a review of relevant ethical issues related to ELX-TEZ-IVA from published literature.

Stakeholder Perspectives

The information in this section is a summary of input provided by the patient and clinician groups who responded to CADTH’s call for input and from clinical experts consulted by CADTH for the purpose of this review. The complete input received for the previous CADTH reviews of ELX-TEZ-IVA is available on the CADTH website (refer to reviews for ELX-TEZ-IVA for patients aged 6 to 11 years and aged 12 years and older).

Patient Input

One patient group, CF Canada, responded to CADTH’s call for patient input for the current review of ELX-TEZ-IVA, which is focused on patients aged 2 to 5 years who have at least one F508del mutation in the CFTR gene.

The patient groups emphasized that CF tremendously impacts those living with the condition, their loved ones, the health systems, and society. The most significant clinical impact is in the lungs, where patients experience progressive scarring of their airways and a progressive decline in lung function. Young children who grow older with CF may suffer from pulmonary exacerbations requiring weeks to months of hospitalization and IV antibiotics. Malnutrition and low BMI are also common consequences of CF among children aged 2 to 5 years. Patients may also suffer from CF-related comorbidities, such as CF-related diabetes and CF-related liver disease. In addition, CF has a significant impact on socialization, mental health, and isolation among patients and caregivers.

The patient input stated that managing CF requires a demanding treatment routine. As the disease progresses, more time and effort, frequent clinic visits, and hospital stays are needed to manage the progressive and debilitating symptoms. This condition has a significant impact on patients’ and caregivers’ day-to-day activities and quality of life, in addition to a huge financial burden for families.

According to the patient group input, an ideal CF treatment would fully address the basic molecular defect in CF and restore normal chloride transport on the cell surface. Patients with CF and their loved ones are seeking treatments that can change the trajectory of the disease, reduce disease symptoms, improve sleep quality and energy levels, and improve both life expectancy and quality of life.

In the patient group input, CF CanACT emphasized the importance of early treatment of CF to prevent disease progression and irreversible damage. Extending access to ELX-TEZ-IVA to patients with CF aged 2 to 5 years would be congruent with the secondary prevention paradigm of CF care, and would decrease the long-term burden of the disease.

Clinician Input

Input From Clinical Experts Consulted by CADTH

Unmet Needs

Similar to the input from the patient groups, the clinical experts consulted by CADTH indicated that there are significant unmet therapeutic needs for patients living with CF. There are no treatments currently available that can meet the most important goals of therapy, including: prolonging survival, preventing the need for lung transplant, slowing the decline in lung function over time, or reverse the course of the disease. In addition, the clinical experts noted that the current standard treatments for CF are burdensome for patients and their caregivers.

Place in Therapy

The clinical experts anticipate that ELX-TEZ-IVA would be used as a preventive therapy with the goal of initiating treatment before the patient develops significant lung disease. The current treatment paradigm would be significantly altered if ELX-TEZ-IVA can successfully prevent or delay progression to end organ disease (e.g., lung transplant). The clinical experts consulted by CADTH and those who responded to the call for clinician input noted that children aged between 2 years and 5 years will often have structural lung disease (e.g., bronchial wall thickening, mucus plugging, bronchiectasis), but that detection is challenging using the tools that are available to evaluate lung function in clinical practice (i.e., spirometry) or as part of a research protocol (e.g., lung clearance index). These early stages of lung abnormalities can be visualized using CT; therefore, despite younger patients with CF often demonstrating normal lung function, the underlying disease will continue to progress.

All of the clinicians who provided input for this review recommended initiating treatment with ELX-TEZ-IVA as soon as possible. This is aligned with the previously published Canadian Clinical Consensus Guideline for Initiation, Monitoring and Discontinuation of CFTR Modulator Therapies for Patients with Cystic Fibrosis, which also recommend that CFTR modulators be initiated at the youngest age possible with the goal of attenuating disease progression and improving clinical status. All stakeholders were in agreement that there are no data to support withholding the initiation of CFTR modulator treatment until clinical symptoms of CF have developed.

Patient Population

For the expanded indication (i.e., those aged 2 to 5 years), the clinical experts consulted by CADTH noted that nearly all patients would initiate therapy with ELX-TEZ-IVA as soon as possible provided it is safe to start to treatment. The clinical experts emphasized that ELX-TEZ-IVA has been a transformative and disease-modifying therapy for CF, and that it would not be appropriate to wait until the patient shows worsening symptoms, more frequent exacerbations, or a decline in lung function to initiate treatment with ELX-TEZ-IVA.

Applicability of Existing Reimbursement Criteria to Pediatrics

In discussions with CADTH, the sponsor noted that nearly all patients in Canada aged 12 years and older who are eligible for treatment have initiated therapy with ELX-TEZ-IVA (some may have elected to discontinue, but all who are interested have been given the opportunity to access the drug). The sponsor similarly stated that nearly all patients in Canada aged 6 to 11 years who wish to initiate treatment will have initiated treatment with ELX-TEZ-IVA by the end of this calendar year. For those who have initiated treatment with ELX-TEZ-IVA, the sponsor noted that initial renewal criteria were met for all patients in Canada who started the therapy and wanted to continue (i.e., 100% of patients met the renewal criteria recommended by CADTH and/or applied by the public drug programs). The clinical experts consulted expressed general agreement with the sponsor’s position, noting that rates of initial access and renewal are very high within their individual clinics. With nearly all patients who are at least 6 years of age having met the initiation and renewal criteria, newly issued CADTH reimbursement criteria focusing exclusively on those aged 2 to 5 years would effectively replace the previous criteria (i.e., although limited to those aged 2 to 5 years, all older patients would have already qualified for initiation and renewal).

The clinical experts consulted by CADTH reviewed the existing criteria that have been recommended for patients aged 6 years and older and noted the following:

  • Baseline measurements: Regarding the baseline measurements that must be completed before initiating treatment with ELX-TEZ-IVA, the clinical experts noted that the following baseline measurements that are currently recommended by CADTH would be problematic to implement, uninformative, and/or not relevant for patients aged 2 to 5 years: baseline FEV1 (spirometry is not performed in patients younger than 6 years of age); baseline frequency of pulmonary exacerbations (exacerbations can be infrequent and it would be challenging establish a reliable baseline); and CFQ-R respiratory domain scores (these are not routinely obtained for patients in pediatric clinics, typically only when conducting research studies). The clinical experts noted that those aged 2 to 5 years would have growth parameters monitored in routine clinical practice. However, it was noted that a majority of patients with CF aged 2 to 5 years do not show reductions in age-standardized BMI, and that BMI percentile can fluctuate in younger patients, especially following periods of acute illness.
  • Renewal criteria: Each of the end points are discussed subsequently, with reflection on the applicability of the existing CADTH criteria to the expanded population of patients aged 2 to 5 years:
    • BMI and BMI z scores: The existing criterion is “no decline in BMI (BMI z score in children) at 6 months compared with the baseline BMI assessment.” The clinical experts noted that 6 months is not sufficient to accurately assess the response to treatment, and that an assessment of BMI at 12 months would be more appropriate. The longer time was suggested to account for events that could temporarily reduce BMI (e.g., increased physical activity in summer months and growth spurts). It was strongly noted that discontinuation of ELX-TEZ-IVA in such patients would not be clinically appropriate.
    • Pulmonary exacerbations: The existing criterion is “a decrease in the total number of days for which the patient received treatment with oral and/or IV antibiotics for pulmonary exacerbations compared with the 6-month period prior to initiating treatment OR a decrease in the total number of pulmonary exacerbations requiring oral and/or IV antibiotics compared with the 6-month period prior to initiating treatment.” The clinical experts indicated that pulmonary exacerbations are less frequent in patients aged 2 to 5 years compared with adults and adolescents. The clinical experts suggested that the existing renewal criterion would be problematic for those aged 2 to 5 years. However, it was emphasized that patients who have not experienced a pulmonary exacerbation or those with a very low annual rate of pulmonary exacerbations would still benefit from the treatment. Similar to the criterion for BMI, it was noted that 12 months would be a more appropriate time frame for evaluating changes in pulmonary exacerbations.
    • CF-related hospitalizations: The existing criterion is “decreased number of CF-related hospitalizations at 6 months compared with the 6-month period prior to initiating ELX-TEZ-IVA treatment.” The clinical experts consulted by CADTH noted that CF-related hospitalization is infrequent and highly variable in patients within the 2- to 5-year age range. As such, this would be very challenging to implement as a criterion for evaluating response to ELX-TEZ-IVA for the purposes of reimbursement.
  • Sweat chloride testing: The previous CADTH recommendation did not include sweat chloride testing as 1 of the initiation or renewal conditions for ELX-TEZ-IVA. The sponsor has requested that “reduction in sweat chloride” be included as a reimbursement condition for ELX-TEZ-IVA in the current review. The pediatric clinical experts agreed with the prior input from the reviews of ELX-TEZ-IVA in patients aged 6 to 11 years and 12 years and older, noting that sweat chloride testing should be not used to evaluate the response to ELX-TEZ-IVA for the purposes of drug reimbursement because it is not clearly predictive of clinically important outcomes and only reflects the mechanism of action of CFTR modulators like ELX-TEZ-IVA. The clinical experts also noted that access to sweat chloride testing can be challenging in some jurisdictions and that the timelines to receive the test results can fluctuate. They also raised important concerns about the capacity of the health system to accommodate repeated sweat chloride testing for all patients with at least one F508del mutation.

Clinician Group Input

Three groups of clinicians responded to CADTH’s call for input: CF CanACT, the CF Canada Health Care Advisory Council, and the Canadian Cystic Fibrosis Clinician groups. The input from the clinician groups identified the same unmet medical needs for patients with CF and potential place in therapy for the drug under review as the clinical experts consulted by CADTH.

According to the clinician group input, the treatment paradigm for CF in children aged 2 to 5 years is lifelong. All clinician groups noted that available treatments address the symptoms and complications of CF and attempt to slow down the eventual fatal progression of the disease without effectively addressing the root cause or reversing the course of the disease. They also have significant side effects and numerous drug interactions. Clinician groups emphasized that ELX-TEZ-IVA is the most effective improvement of the existing CFTR modulators as it addresses the underlying disease process which helps in delaying disease progression and the need for other therapies, including lung transplant. Therefore, any patient with CF who has at least 1 copy of F508del could potentially benefit from ELX-TEZ-IVA.

Drug Program Input

Input was obtained from the drug programs that participate in the CADTH reimbursement review process. The clinical experts consulted by CADTH provided advice on the potential implementation issues raised by the drug programs.

Table 2. Responses to Questions From the Drug Programs.

Table 2

Responses to Questions From the Drug Programs.

Clinical Evidence

Systematic Review

Description of Studies

The evidence identified in the current review of ELX-TEZ-IVA that addressed the expanded patient population (i.e., those aged 2 to 5 years) included Study 111, a 24-week, open-label, phase III, nonrandomized, single-arm, 2-part (A and B) study. Study 111 was conducted in 2 parts:

  • Part A (n = 18) consisted of a 15-day treatment period conducted to evaluate the pharmacokinetics and safety and tolerability of ELX-TEZ-IVA.
  • Part B (n = 75) consisted of a 24-week treatment period conducted to assess safety and tolerability (primary objective) and pharmacokinetics, pharmacodynamics, and efficacy (secondary objective).

Patients were eligible to be included in Study 111 if they had received a diagnosis of CF and were aged 2 to 5 years (inclusive). All patients had an F508del CFTR mutation that was either F/MF (69.3%) or F/F (30.7%). Patients were excluded from the study if they had any comorbidities that could impact treatment outcomes, or if they had received a prior hematological or solid organ transplant. The trial excluded patients with a history of colonization with Burkholderia cenocepacia, Burkholderia dolosa, and/or Mycobacterium abscessus. Patients were also considered to be ineligible if they reported an acute upper or lower respiratory infection, a pulmonary exacerbation, or changes in therapy (including antibiotics) for pulmonary disease within 4 weeks before the first dose of the study drug. Patients with a history of solid organ or hematological transplant were excluded, as were patients with abnormal laboratory values (e.g., hemoglobin < 10 g/dL), abnormal liver function, or abnormal renal function.

Safety and tolerability were the primary end points in Study 111. Secondary end points were absolute change from baseline in sweat chloride through 24 weeks and absolute change from baseline in LCI2.5. Changes from baseline in growth parameters (BMI, BMI z score, weight, weight z score, height, and height z score) were evaluated as additional efficacy end points, but no statistical analyses were conducted. Descriptive statistics were provided for pulmonary exacerbations and CF-related hospitalizations in Study 111. LCI2.5 was only evaluated in patients who were at least 3 years of age at the time of screening (n = 50).

Efficacy Results

Treatment with ELX-TEZ-IVA resulted in a within-group improvement (reduction) in sweat chloride from baseline through 24 weeks (least squares [LS] mean absolute change was –57.9 mmol [95% confidence interval (CI), –61.3 to –54.6]; nominal P < 0.0001). The reduction from baseline was observed at all postbaseline assessments (i.e., weeks 4, 12, and 24). Results for the subgroup analyses based on CFTR genotype were–70.0 mmol/L (95% CI, –75.4 to –64.5) in the F/F group and –52.6 mmol/L (95% CI, –56.9 to –48.4) in the F/MF group.

Among those patients who were assessed, treatment with ELX-TEZ-IVA resulted in an improvement (reduction) in LCI2.5 through 24 weeks (within-group LS mean absolute change from baseline –0.83 [95% CI, –1.01 to –0.66]; nominal P < 0.0001). The reduction from baseline was observed at all postbaseline assessments (i.e., weeks 4, 12, and 24). The results were similar in the F/F and F/MF genotype subgroups (LS mean change: –0.89 [95% CI, –1.15 to −0.63] and –0.82 [95% CI, –1.06 to –0.57], respectively).

Sixteen percent of patients experienced a pulmonary exacerbation event through 24 weeks (each patient experience 1 event), with an annualized event rate of 0.32 per year. One patient experienced a pulmonary exacerbation that required hospitalization. There were no CF-related hospitalizations in Study 111.

The absolute changes from baseline in growth end points at 24 weeks were: 0.10 (95% CI, 0.00 to 0.20) for BMI z score; 0.02 (95% CI, –0.04 to 0.09) for body weight z score; and –0.06 (95% CI, –0.11 to 0.00) for height z score.

Harms Results

The overall percentage of patients who experienced at least 1 adverse event (AE) was 98.7% (nearly all were mild [62.7%] or moderate [36.0%] in severity). These AEs included cough (61.3%), increased alanine transaminase (ALT )(10.7%), rhinorrhea (33.3%), increased aspartate aminotransferase (AST) (5.3%), rash (16.0%), pyrexia (34.7%), vomiting (28.0%), COVID-19 (18.7%), nasal congestion (17.3%), upper respiratory tract infection (14.7%), decreased appetite (12.0%), and infective pulmonary exacerbation of CF (10.7%). Two patients (2.7%) experienced serious adverse events (SAEs): 1 patient with anal incontinence, urinary incontinence, and abnormal behaviour [wording from original source]); and 1 patient with an infective pulmonary exacerbation of CF. One patient (1.3%) discontinued treatment due to an SAE and 5 patients (6.7%) had AEs leading to treatment interruption. For AEs of special interest, 8 patients (10.7%) experienced elevated transaminase events and 15 patients (20.0%) experienced rash events (all events were mild or moderate in severity). Two patients experienced rash events leading to treatment interruption. There were no study discontinuations due to rash events or elevated transaminase events.

Critical Appraisal

Internal Validity

Study 111 was conducted in a manner similar to all other pivotal studies for the use of CFTR modulators in patients aged 2 to 5 years (i.e., expansion of approval indications for Orkambi and Kalydeco). Each of these studies was conducted in 2 parts, with part A involving a small number of patients (n = 18 for Study 111) with a primary objective of evaluating pharmacokinetics, and part B enrolling more patients (n = 75 for Study 111) with the primary objective of evaluating safety and tolerability. As with the other trials for CFTR modulators in patients aged 2 to 5 years, ELX-TEZ-IVA was administered in an open-label manner in Study 111 and there was no comparator group for either part A or part B. The limited number of secondary efficacy end points evaluated in the study were objective and unlikely to be influenced by the open-label administration of a CFTR modulator (i.e., change from baseline in sweat chloride concentration and change from baseline in LCI2.5).

Pulmonary exacerbations were only evaluated with descriptive statistics and there were no prebaseline or postbaseline comparisons of event rates. In response to an inquiry from CADTH regarding why pulmonary exacerbations were not included as an efficacy end point, the sponsor reported that, similar to the pediatric trial for patients aged 6 to 11 years, exacerbations occur less frequently in younger patients relative to older patients. As Study 111 was a single-arm trial without a defined pretreatment evaluation period, together with the low pulmonary exacerbation rates in the study population, comparison to a pretreatment event rate was not possible.

External Validity

Eligibility and diagnostic criteria used to screen patients for Study 111 were similar to those used in the other phases of the ELX-TEZ-IVA clinical development program (e.g., Studies 106 and 116 for patients aged 6 to 11 years, and Studies 102, 103, 104, and 109 for patients aged 12 years and older). As noted in the previous CADTH review of ELX-TEZ-IVA, these criteria are generally consistent with Canadian clinical practice for diagnosing patients with CF. As all Canadian provinces and territories have instituted newborn screening, diagnosis of CF and confirmation of genotyping would typically occur early in the child’s life (e.g., an average of 1 month after birth). As such, there would be no changes in diagnostic testing requirements to establish patient eligibility based on CF diagnosis and genotype for the revised age range for ELX-TEZ-IVA.

The clinical experts consulted by CADTH noted that the baseline growth parameters for the patients in Study 111 offered a reasonable reflection of the typical patient in Canadian practice.

Change from baseline in lung function was evaluated as a secondary efficacy end point in Study 111 using LCI2.5. This is reflective of regulatory guidance, which has noted that spirometry may not be sensitive enough to detect treatment differences in children with cystic fibrosis. In addition, spirometry is not typically performed in patients younger than 6 years in Canada, and FEV1 has not been used as a clinical trial end point in any CFTR modulator studies for those younger than 6 years. LCI is used in CF clinical trials as it may be more sensitive in identifying early underlying structural deficiencies within the lungs of patients with CF that cannot be detected using spirometry. Similar to spirometry assessments, the LCI test can be challenging to perform accurately with young children. In Study 111, the sponsor noted that LCI was only performed with patients who were aged at least 3 years at the time of screening. Although LCI is used as an end point in clinical studies, as noted previously, it is not routinely used in Canadian clinical practice and the clinical relevance of differences in this end point have not been characterized. The clinical experts consulted by CADTH indicated that LCI is not reliably correlated with FEV1. A literature review conducted by CADTH found that variable correlation was observed between FEV1 and LCI in children.

ELX-TEZ-IVA was added to the existing therapeutic regimens used by patients, which is reflective of how ELX-TEZ-IVA would be administered in clinical practice. The clinical experts consulted by CADTH indicated that the background therapies used in Study 111 were similar to what would be anticipated in Canadian clinical practice, with the following exacerbations: all patients in Canadian practice would be supplementing with vitamins, and the use of mucolytics (i.e., dornase alfa and inhaled hypertonic saline) could be slightly lower for patients aged 2 to 5 years in Canada.

The 24-week study treatment periods were sufficient for observing change from baseline in sweat chloride and LCI2.5 in Study 111; however, the clinical experts consulted by CADTH suggested that 24 weeks is unlikely to be enough time to observe meaningful changes in BMI for a younger patient population that is relatively healthy. In addition, the absence of a control group in Study 111 limits the ability to interpret the results of change from baseline in the growth parameters.

Long-Term Extension Studies

Patients who completed Study 111 were eligible to enrol in an open-label extension study. However, the sponsor reported that the interim results of the extension study were not available at the time of filing the application with CADTH.

Indirect Comparisons

Feasibility of ITC in Patients Aged 2 to 5 Years

The sponsor conducted an indirect treatment comparison (ITC) to compare the clinical efficacy of ELX-TEZ-IVA in Study 111 with other CFTR modulators in patients with F/F and F/MF mutations to generate inputs needed for the cost-effectiveness analysis. A meta-analysis approach via mixed-effects model for repeated measures (MMRM) was used with individual patient-level data from relevant trials, with data from all comparators being included in 1 model for each genotype. The sponsor concluded that the ITC was not feasible due to the small number of patients in this age group, which reduced the power to detect differences between ELX-TEZ-IVA, LUM-IVA, and/or placebo. As such, the sponsor did not include the ITC comparison in their submission to CADTH and used estimates from the previous CADTH submission for patients aged 6 to 11 years to use as assumptions within their economic model.

ITCs in Patients Aged 6 to 11 Years and 12 Years and Older

To inform the pharmacoeconomic model, the sponsor submitted estimates of clinical efficacy of ELX-TEZ-IVA compared to placebo derived from ITCs that were previously conducted for patients aged 6 to 11 years and 12 years and older, using individual patient data from relevant phase III randomized controlled clinical trials.

The sponsor conducted a single indirect comparison for patients aged 6 to 11 years with an F/F genotype to derive relative estimates of clinical efficacy for: ELX-TEZ-IVA versus LUM-IVA, ELX-TEZ-IVA versus placebo, and ELX-TEZ-IVA versus TEZ-IVA. TEZ-IVA is not currently approved by Health Canada or reimbursed by the Canadian public drug programs for use in patients aged 6 to 11 years. To conduct the primary indirect comparisons, the sponsor extracted 24-week individual patient data for those with an F/F genotype from the following studies: Study 106B for ELX-TEZ-IVA (N = 29), pooled data from Study 809-109 and Study 809-011B for LUM-IVA (N = 160), and Study 661-113B (N = 61) for TEZ-IVA. Additional sensitivity analyses were performed using 8-week data. The sponsor reported the following indirect estimate of effect for ELX-TEZ-IVA compared with placebo for absolute change from baseline through 24 weeks: | || || || || | for ppFEV1. The primary limitation of the ITC was the difference in study design across the included studies (Studies 106B, 809-011B, and 661-113B were single-arm, open-label trials; and Studies 809-109 and 661-115 were double-blind, placebo-controlled trials) and differences in baseline characteristics.

Studies Addressing Gaps in the Evidence From the Systematic Review

The sponsor did not include any additional studies to address gaps in the pivotal trial evidence.

Ethical Considerations

Patient group, clinical expert, and drug program input gathered during this CADTH review, as well as relevant literature, were reviewed to identify ethical considerations relevant to the use of ELX-TEZ-IVA for the treatment of CF in patients aged 2 to 5 years who have at least one F508del mutation in the CFTR gene.

Ethical considerations identified in this review included those related to the following.

  • Diagnosis, treatment, and experiences of CF: Ethical considerations in the context of CF highlighted the physical and psychosocial burden of CF on patients, families, and caregivers.
  • Evidence and evaluation of ELX-TEZ-IVA in patients aged 2 to 5 years: Clinical trial evidence indicated that ELX-TEZ-IVA was well-tolerated in study participants aged 2 to 5 years, with few SAEs, and with the recommendation for ongoing monitoring of liver enzymes. However, as the trial was not primarily designed to assess efficacy, the determination of efficacy in patients aged 2 to 5 years for the purposes of regulatory approval was extrapolated from studies conducted in older patients with CF. Extrapolation may offer benefits such as avoiding exposing vulnerable patients, such as children, to unnecessary research and extending access to therapy in patient populations that may be difficult to study or cannot be studied in clinical trials. However, extrapolation also presents potential risks if efficacy is not generalizable and thus overestimates or underestimates real-world effectiveness across different populations. Long-term monitoring is required to understand long-term safety, efficacy, and comparative effectiveness of ELX-TEZ-IVA in patients aged 2 to 5 years. The lack of long-term efficacy and comparative effectiveness data limits the ability to accurately model and assess the cost-effectiveness of ELX-TEZ-IVA for use in patients aged 2 to 5 years.
  • The use of ELX-TEZ-IVA in patients aged 2 to 5 years: Clinical experts noted that, given the efficacy data in patients aged 6 years and older, they expected ELX-TEZ-IVA to benefit patients aged 2 to 5 years who have at least one F508del mutation in the CFTR gene. As a result, they suggested that they would recommend prescribing ELX-TEZ-IVA for children aged 2 to 5 years, given the expected benefits of preventive treatment to prevent structural lung damage, the lack of effective alternatives, and the generally favourable safety and tolerability profile in this age group. As an orally administered medication, ELX-TEZ-IVA is relatively accessible and easy to administer for patients or their caregivers, including relative to alternate therapies.
  • Health systems considerations: Expensive drugs for rare diseases, such as ELX-TEZ-IVA, raise ethical considerations related to distributive justice and equitable access, the sustainability of health care budgets and consideration of opportunity costs, and fair pricing of pharmaceuticals. As a highly expensive medication, the cost of ELX-TEZ-IVA could present challenges for provincial drug budgets where the reimbursement of ELX-TEZ-IVA may have a disproportionately large budget impact. There is a need to address potential inequities in access due to inconsistent reimbursement and/or insurance coverage across and within jurisdictions in Canada.

Economic Evidence

Table 3. Cost and Cost-Effectiveness.

Table 3

Cost and Cost-Effectiveness.

Budget Impact

CADTH identified the following key limitations with the sponsor’s analysis: the sponsor’s adjustment of drug costs by a compliance rate for patients underestimates drug costs and the resulting budget impact, the sponsor’s estimate of the proportion of patients switching treatments from LUM-IVA to ELX-TEZ-IVA upon ELX-TEZ-IVA reimbursement may be underestimated, and there is uncertainty regarding the proportion of patients with public drug coverage. The CADTH reanalysis assumed 100% compliance for all drugs. In the CADTH base case, the reimbursement of ELX-TEZ-IVA for the treatment of CF in patients aged 2 to 5 years with at least one F508del CFTR mutation is expected to be $42,404,017 in year 1, $46,295,984 in year 2, and $48,029,320 in year 3. Therefore, the 3-year total is $136,729,321. A CADTH scenario analysis found the budget impact to be sensitive to assumptions around the proportion of patients with public drug coverage.

CDEC Information

Members of the Committee:

Dr. James Silvius (Chair), Dr. Sally Bean, Mr. Dan Dunsky, Dr. Alun Edwards, Mr. Bob Gagne, Dr. Ran Goldman, Dr. Allan Grill, Mr. Morris Joseph, Dr. Christine Leong, Dr. Kerry Mansell, Dr. Alicia McCallum, Dr. Srinivas Murthy, Ms. Heather Neville, Dr. Danyaal Raza, Dr. Emily Reynen, and Dr. Peter Zed.

Meeting date: September 28, 2023

Regrets: None

Conflicts of interest: None

Disclaimer: The information in this document is intended to help Canadian health care decision-makers, health care professionals, health systems leaders, and policy-makers make well-informed decisions and thereby improve the quality of health care services. While patients and others may access this document, the document is made available for informational purposes only and no representations or warranties are made with respect to its fitness for any particular purpose. The information in this document should not be used as a substitute for professional medical advice or as a substitute for the application of clinical judgment in respect of the care of a particular patient or other professional judgment in any decision-making process. The Canadian Agency for Drugs and Technologies in Health (CADTH) does not endorse any information, drugs, therapies, treatments, products, processes, or services.

While care has been taken to ensure that the information prepared by CADTH in this document is accurate, complete, and up-to-date as at the applicable date the material was first published by CADTH, CADTH does not make any guarantees to that effect. CADTH does not guarantee and is not responsible for the quality, currency, propriety, accuracy, or reasonableness of any statements, information, or conclusions contained in any third-party materials used in preparing this document. The views and opinions of third parties published in this document do not necessarily state or reflect those of CADTH.

CADTH is not responsible for any errors, omissions, injury, loss, or damage arising from or relating to the use (or misuse) of any information, statements, or conclusions contained in or implied by the contents of this document or any of the source materials.

This document may contain links to third-party websites. CADTH does not have control over the content of such sites. Use of third-party sites is governed by the third-party website owners’ own terms and conditions set out for such sites. CADTH does not make any guarantee with respect to any information contained on such third-party sites and CADTH is not responsible for any injury, loss, or damage suffered as a result of using such third-party sites. CADTH has no responsibility for the collection, use, and disclosure of personal information by third-party sites.

Subject to the aforementioned limitations, the views expressed herein are those of CADTH and do not necessarily represent the views of Canada’s federal, provincial, or territorial governments or any third-party supplier of information.

This document is prepared and intended for use in the context of the Canadian health care system. The use of this document outside of Canada is done so at the user’s own risk.

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The copyright and other intellectual property rights in this document are owned by CADTH and its licensors. These rights are protected by the Canadian Copyright Act and other national and international laws and agreements. Users are permitted to make copies of this document for noncommercial purposes only, provided it is not modified when reproduced and appropriate credit is given to CADTH and its licensors.

Redactions: Confidential information in this document may be redacted at the request of the sponsor in accordance with the CADTH Drug Reimbursement Review Confidentiality Guidelines.

About CADTH: CADTH is an independent, not-for-profit organization responsible for providing Canada’s health care decision-makers with objective evidence to help make informed decisions about the optimal use of drugs, medical devices, diagnostics, and procedures in our health care system.

Funding: CADTH receives funding from Canada’s federal, provincial, and territorial governments, with the exception of Quebec.

Indication: For the treatment of cystic fibrosis in patients aged 2 and older who have at least one F508del mutation in the cystic fibrosis transmembrane conductance regulator gene.

Sponsor: Vertex Pharmaceuticals (Canada) Incorporated

Final recommendation: Reimburse with conditions

Copyright Notice

Copyright © 2023 - Canadian Agency for Drugs and Technologies in Health. Except where otherwise noted, this work is distributed under the terms of a Creative Commons Attribution-NonCommercial- NoDerivatives 4.0 International licence (CC BY-NC-ND).

Bookshelf ID: NBK599836PMID: 38301053

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